Authors: E. V. Pitjeva
Journal: Transactions of IAA RAS vol. 40
Keywords: Astrometry, VLBI, Ephemerides, Orientation
The modern planetary ephemerides are based generally on ranging data of planets and spacecraft. However, the orientation of planet ephemerides with re- spect to ICRF has been made by the ICRF-based VLBI measurements of spacecraft near planets using the following two types of VLBI measurements: one component made by tracking stations from NASA DSN, and VLBA measurements. This paper shows a progress in accuracy of orientation angles (up to fractions of mas) as a result of adding new VLBI points (VLBA data), as well as an increase of the accuracy of measurements. Also, usage of these measurements allows us to improve planetary ephemerides. The orientation and the improvement were made within the new version of EPM2015 (Ephemerides of Planets and the Moon) at IAA RAS, available via the FTP server ftp://quasar.ipa.nw.ru/incoming/EPM/.